1. Field of the Invention
The present invention relates in general to electrochemical devices, and, more particularly, to reversible electrodeposition devices having electrochemical media which serve to enhance both durability and reversible deposition uniformity of the electrodeposition devices relative to the same without such electrochemical media.
2. Background Art
Electrodeposition devices have been known in the art for several years and are the subject of a plurality of United States Patents, including, for example, U.S. Pat. No. 5,056,899 entitled “Material For Light Modulation and Manufacturing Processes,” U.S. Pat. No. 5,903,382 entitled “Electrodeposition Cell With High Light Transmission,” U.S. Pat. No. 5,923,456 entitled “Reversible Electrochemical Mirror,” U.S. Pat. No. 6,111,685 entitled “Reversible Electrochemical Mirror (REM) With Improved Electrolytic Solution,” and U.S. Pat. No. 6,166,847 entitled “Reversible Electrochemical Mirror For Modulation Of Reflected Radiation”—just to name a few.
Generally, electrodeposition devices can be categorized into two groups, namely: “rocking chair” type electrodeposition devices wherein deposition/plating occurs via a plating-solution-plating mechanism (e.g. U.S. Pat. No. 5,903,382), and electrodeposition devices wherein deposition takes place while oxidation of a halide occurs at the anode (e.g. U.S. Pat. No. 5,056,899). While the above-identified electrodeposition devices have been known in the art for years, operational limitations and device configurations remain largely problematic, or at least, less than desirable for commercial applications.
For example, some electrodeposition devices can be susceptible to dendrite formation at or near an electrode, which, in turn, can adversely affect the electrochemical performance of the device, and in some circumstances render the electrodeposition device inoperable—even after only relatively few cycles (i.e. a transition from a high transmission state to a low transmission state). Moreover, several of the “rocking chair” type electrodeposition devices incorporate specially configured anodes which are distributed in localized, patterned areas and/or utilize a specially modified cathode as is disclosed in U.S. Pat. No. 5,923,456. Such configurations can materially increase manufacturing complexity, as well as compromise optical performance due to gridlines, dots, etcetera.
Electrodeposition devices as disclosed in U.S. Pat. No. 5,056,899 suffer from numerous drawbacks, the details of which are well disclosed in U.S. Pat. No. 5,903,382 and related cases.
It has now been surprisingly discovered that electrodeposition devices can be fabricated which exhibit enhanced durability by controllably selecting concentrations of anodic and/or cathodic materials within the electrochemical media without such complex device configurations. It has also been surprisingly discovered that incorporating redox buffers into the electrochemical media further enhances the electrochemical performance of such electrodeposition devices. (See, for example, U.S. Pat. Nos. 6,188,505; 6,310,714; and 6,433,914—all of which are hereby incorporated herein by reference in their entirety).
It is therefore an object of the present invention to provide an electrodeposition device having an electrochemical medium that remedies the aforementioned detriments and/or complications associated with conventional electrodeposition devices.
These and other objectives of the present invention will become apparent in light of the present specification, claims, and drawings.